It seems like a heated topic!!
Me and my girlfriend are in the same position, where we were quite fit, but have let it slip a little

...it seems hard to motivate yourself after a hard day at work, but we're starting walking after meals, just 20 minutes in the evening...
It doesn't have to be alot of exercise, but we're feeling better already...
Maybe that's the way to go, a little but often!!
Rich